Genetic Profiles Determine Metastasis Source

A study has shown that by isolating the genes that are expressed in head and neck cancer as well as those expressed in lung cancer in smokers, researchers were able to predict precisely if patients with lung masses had developed lung cancer or metastases from another source. The study results were presented at the annual Clinical Congress of the American College of Surgeons (ACS) in New Orleans (LA, USA) in October 2004.

Now the researchers are making their genetic algorithms available to doctors throughout the world to help them decide whether an individual patient has advanced cancer that spread from the head and neck to the lung, or whether the patient has other metastatic sources that may be treated individually. Smokers have a high risk for developing cancer in the neck, mouth, jaw, and lung, but it is often difficult to identify the primary source of the disease because all cancers related to smoking appear the same in tissue samples under the microscope--as squamous cell carcinoma.

"People who have been smoking all their lives often have tumors in the head, in the neck, or in the tongue or jaw where the tobacco has rubbed against the inner lining of the mouth,” explained Sunil Singhal, M.D., a fellow in thoracic surgery at the University of Pennsylvania (Philadelphia, USA). "These patients also often have
masses in the chest on x-rays. There has been no way to determine whether a patient has a cancer that has spread or several different cancers.”

Dr. Singhal and his associates hope their genetic profiles of cancers related to smoking will become the new gold standard for determining if a patient has primary or metastatic disease. "We are telling physicians to look at our genes or even send tissue samples to us. We're hoping to get to the point where physicians can look on the Web, compare a patient's genetic profile with the gold standard, and be able to immediately determine what type of cancer he or she has,” said Dr. Singhal. In the study, Dr. Singhal extracted ribonucleic acid from eight smokers with lung squamous cell carcinoma and eight smokers with head and neck squamous cell carcinoma.

The researchers examined more than 44,000 genes through microarray technology to find 65 genes that could distinguish lung from head and neck cancer. After constructing statistical algorithms for each disease, the researchers prospectively classified 24 patients with an unknown primary source of head and neck or lung cancer, and they correctly identified all 17 who later were confirmed to have head and neck cancer and all seven who had lung cancer.




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